The present invention relates to optical amplification and, in particular, it concerns optical amplification in semiconductors, particularly silicon, by optical pumping and/or non-homogeneous heating.
There is presently a great deal of interest in the pursuing of semiconductors as basic materials for lasers and optical amplifiers for optical networks. Most of existing semiconductor lasers and amplifiers are based on direct band gap semiconductor materials. At present, Silicon is not considered a favorable candidate for these applications, by virtue of indirect band gap structure. On the other hand, light stimulated emission properties of GaP, also an indirect band-gap semiconductor has been reported and light-emitting diodes (LEDs) based on this material are commercially available [1]. Regarding doped Silicon, a massive effort in order to develop lasers and amplifiers is taking place these days worldwide (see Refs. [2,3] for a review on the subject). Experimental observation of the stimulated emission in bulk Silicon was not reported to-date to the best of our knowledge [4], since Basov, et al [5], and recently Trupke, et al [6] theoretically predicted this possibility. Reports on gain included Er+-doped silicon and silicon dioxide structures [7] and structures not based on the original crystalline structure (nano-crystals, nano-layers etc) [2]. Gain was also attained via non-linear processes e.g. stimulated Raman scattering [8] and multiwave mixing [9], the mechanisms present in many materials. Our main goal here is the disclosure of methods for attaining stimulated emission in Silicon. Stimulated emission is in the essence of laser action or optical amplification of light signals.